Implantable medical devices, including cardiac rhythm management devices such as pacemakers and implantable cardioverter/defibrillators, typically have the capability to communicate data with an external device called an external programmer via a radio-frequency telemetry link. One use of such an external programmer is to program the operating parameters of an implanted medical device. For example, the pacing mode and other operating characteristics of a pacemaker are typically modified after implantation in this manner. Modern implantable devices also include the capability for bidirectional communication so that information can be transmitted to the programmer from the implanted device. Among the data that may typically be telemetered from an implantable device are various operating parameters and physiological data, the latter either collected in real-time or stored from previous monitoring operations. External devices for remote monitoring may also receive telemetry data from an implantable device where, for the convenience of the patient, the communications must take place over greater distances than with the typical external programmer.